Recently, a technology of treating (for example, cutting and crushing) a tissue such as the crystalline lens of a patient's eye (the cornea of a patient's eye) by performing irradiation with a laser beam has been proposed. For example, in an apparatus disclosed with reference to Patent Documents 1 and 2, a laser is concentrated on a target position of an ocular tissue, thereby forming a laser spot. As a result, the ocular tissue is mechanically disrupted (cut).
Such an apparatus includes an adsorption unit (an eyeball fixing unit) which adsorbs an eyeball in order to prevent the eyeball from moving during laser irradiation, and an interface unit (for example, a contact unit and a liquid interface) which optically guides (performs positioning of an optical system) the laser spot accurately.